The continuing incidence of oil spillage into both marine and inland waterways due to shipping accidents results in enormous annual costs both financially to the shipping and insurance industries and environmentally. Many spill incidents occur in bad weather or in remote locations. Current systems for ameliorating oil spills require that specialized spill-response ships containing unique heavy equipment reach the site of the spill quickly, which requires relatively calm waters. There is a limited number of units of specialized equipment, and they are not easily transported. Thus, in many cases, response to the spill is delayed for many hours or even days. The impact of a spill is greatly increased by both bad weather and delayed response. Spill damage can be mitigated if response is rapid, even in rough-water conditions.
An additional problem is the high cost of disposal of the recovered material. Current recovery systems create large quantities of waste, which must be disposed of as hazardous waste at high financial cost. This problem can be solved by employing a system that allows for recycling, reclaiming, or low cost disposal.
Known systems for the clean-up of oil spilled on water fall into two categories: (1) absorption or adsorption (sorbing) of the oil, or (2) skimming of the oil, typically in conjunction with containment.
Many materials are known to be oil-absorbent or oil-adsorbent, such as wood chips, activated carbon, wool, cotton balls, corn husks, duck feathers, and various synthetic polymeric materials. A number of polymeric materials (polypropylene, polyester, polyurethane, vinyl polymers, and others) are known to absorb or adsorb crude or refined oil. Systems for applying these materials to oil spills are less developed. Application of materials to oil have been largely limited to two types: (1) spraying particles of the oil-sorbing material on the spill, or (2) placing the material inside booms or other barriers that surround the spill.
Either method creates severe collection problems for sorbent material in particulate form, including sinking of the oil-loaded material, loss of the oil-loaded material due to dispersion by wave action or high winds, and dissolution of the oil-sorbent material in the oil spill. These problems are exacerbated when the spill occurs in bad weather or near shorelines. In addition, because 90% of spilled oil is typically located in 10% of the spill area, the dissolution problem can be particularly troublesome inside barriers. Further, the application of oil-sorbing material typically employs spill boats, which rely on availability of the boat and access to the spill. Both of these can be a severe problem in remote locations or bad weather.
Containers for oil-sorbing materials are known. These systems generally employ pillow or bale shaped containers. However, these containers have a tendency to pile up on top of each other, creating an undesirable condition in which a significant amount of the sorbent material is either below the waterline or floating above the oil, in either case out of contact with the oil. In addition, the large cross section of these types of containers tends to result in an "oil lock-out" phenomenon, in which the surface of the material becomes saturated with oil, effectively preventing oil migration to the center of the material. These containers also have a propensity for folding over on themselves in heavy seas, thereby entrapping water, which causes them to sink.
On the other hand, oil-containment systems utilize booms to surround the spill until the oil can be collected. Boom systems have a number of designs, some of which employ oil sorbent materials in their construction. However, oil-sorbent booms are not designed to sorb substantial amounts of oil, but rather are generally used to retrieve a sheen or a small oil spill or to prevent the spill from expanding or reaching a protected area such as a shoreline until it can be collected by mechanical means, typically utilizing skimmers or oil-recovery boats.
Containment systems employing traditional booms have numerous problems. Deployment of some booms requires specialized equipment, which can be slow and difficult. If the spill is large, surrounding the spill may not be possible due to lack of sufficient boom resources. All of these problems can delay response to the spill. Therefore, boom and skimmer systems do not work well in rough water or near obstacles.
Delayed response to a spill results in a number of deleterious changes. A spill spreads uncontrollably and rapidly to a thin layer on water (less than 1 mm in many cases), making containment extremely difficult if not impossible. If close to shore, the oil may wash ashore, causing severe environmental damage. Lighter fractions of the oil (volatile organic compounds) are released into the atmosphere, resulting in hydrocarbon air pollution. The oil will undergo aging and emulsification, which can cause the oil to sink, making cleanup even more difficult. All of these changes cause the cleanup of the spill to become much more difficult, increase the environmental impact, and raise the financial cost of the cleanup.
There has been a need for some time, therefore, for an oil-recovery system that would (1) permit faster response, (2) work better in adverse conditions, such as rough water or near shorelines and obstacles, (3) prevent more of the oil from sinking, (4) contain the extent of the oil spill more quickly, (5) permit easier and more flexible deployment, (6) allow for easier collection, (7) permit economical recycling or disposal of the collected oil, and better protect the environment.
Accordingly, it is a primary object of the present invention to achieve a more effective system for recovering oil from the surface of bodies of water, such as oceans, lakes, or rivers.
It is another object of the invention to provide methods and apparatus for applying oil-absorbent or oil-adsorbent materials to an oil spill quickly and easily, accurately, and with minimal disturbance of the environment.
It is another object of the invention to provide methods and apparatus for effectively containing water-borne oil spills, even under adverse conditions or near shorelines, rocks, and reefs.
It is another object of the invention to provide methods and apparatus for ameliorating oil spills both by containment, such as within a barrier, and by entrapping the oil in an oil-sorbent material.
It is another object of the invention to provide a means of improving the collection of spilled oil.
It is another object of the invention to provide systems for controlling and removing oil spills in areas of a body of water that are remote from collection vessels or in areas where shipping hazards or the oil itself prevent safe vessel operation.
It is another object of the invention to provide collection systems that do not need to rely on the presence of specialized boats or vessels but can work with them.
It is another objective of the invention to provide systems for controlling oil spills that provide for the economical recycling of the collected oil as fuel.
It is another objective of the invention to provide systems for controlling oil spills that provide for the disposal of the oil through in-situ burning of the oil.
The present invention achieves the above and other objectives by use of a plurality of water- and oil-porous containers or sacks that are partially filled with a number of generally toroidal bodies of a polymer material that entraps oil and including mesh fragments scattered throughout the bodies. Each sack is sewn in a novel way, with a perimeter stiffening ring, to retain a flat profile, and has a netting that closes to help inhibit outflow of the oil when the sack is retrieved. When deployed from ship or by air onto a spill, the sacks spread into a pancake shape and the polymer bodies form a single layer that retains the oil. The inventive sacks will float indefinitely without releasing the oil or allowing it to emulsify, so the oil can remain in place until collection efforts are feasible. The sacks can be burned in situ, or standard fishing boats or specialized collection boats can be used to retrieve the sacks, and the collected material can be burned to capture the energy content of the oil or processed to separate the oil from the polymer. The inventive sacks can be used in conjunction with other, known containment or retrieval equipment, such as booms or skimmers, if desired.
Thus, the inventive systems, devices, and methods can be used to permit easy and quick deployment of containment equipment, even if a spill is in an inconvenient or distant location, effective control of the spilled oil during any delays in recovery, and comparatively inexpensive and easy collection of the oil during the clean-up stage. The system is specifically designed for rapid deployment and efficiency in rough water.